Rare earth oxysulfide luminescent material and preparation method therefor

Abstract

Provided is an oxysulfide luminescent material. The luminescent material has a general chemical formula of Ln 2−x O 2 S:Eu x 3+ @M y , wherein@ is coating, Eu is doped in Ln 2−x O 2 S, Ln 2−x O 2 S:Eu x 3+ has a porous structure, and M is located in pores of the Ln 2−x O 2 S:Eu x 3+ . In the oxysulfide luminescent material, metal nano particles coating is used to form a core-shell structure, which increases luminescent efficiency of the oxysulfide luminescent material in a same excitation condition; in addition, a hollow structure is formed between a core and a shell layer of the oxysulfide luminescent material, which effectively reduces usage of rare earth elements in the shell layer and lowers cost of the luminescent material. Also provided is a preparation method for the oxysulfide luminescent material.

What is claimed is: 
     
       1. An oxysulfide luminescent material having a general chemical formula of Ln 2−x O 2 S:Eu x   3+ @M y , wherein Eu 3+  is doped in Ln 2−x O 2 S; Ln 2−x O 2 S:Eu x   3+  has a porous structure, and @ is coating; Ln is selected from Y, Gd and La; M is at least one of Ag, Au, Pt, Pd and Cu nanoparticles; x is in a range of 0<x≦0.2; y is a molar ratio of M to Ln 2−x O 2 S:Eu x   3+  and y is in a range of 0<y≦1×10 −2 . 
     
     
       2. The oxysulfide luminescent material according to  claim 1 , wherein x is in a range of 0.001≦x0.1. 
     
     
       3. The oxysulfide luminescent material according to  claim 1 , wherein y is in a range of 1×10 −5 ≦y≦1×10 −3 . 
     
     
       4. A method for preparing an oxysulfide luminescent material, comprising:
 mixing and reacting a solution of salt containing metal M with an additive and a reducing agent to prepare a colloid containing M, wherein the metal M is at least one of Ag, Au, Pt, Pd and Cu nanoparticles; the additive is at least one of polyvinylpyrrolidone, sodium citrate, cetyl trimethyl ammonium bromide, sodium dodecyl sulfate and sodium dodecyl sulfonate; 
 adding the colloid containing M to an ethanol solution of sucrose or glucose to obtain a mixed solution, then heating the mixed solution at 120° C.-200° C. to form a solution of C@M, and centrifuging the solution of C@M, washing and drying to obtain C@M nanospheres; @ is coating M with C, and a molar ratio of M to C from sucrose or glucose is in a range of 5×10 −4 −5×10 −2 ; 
 adding the C@M nanospheres to a solution of Ln 3+  and Eu 3+  according to a molar ratio of Ln 3+  to Eu 3+  to M which is (2-x):x:y; regulating the pH value of the solution to 2-3, followed by adding oxalic acid and regulating the pH value to 8-9 to obtain a liquid suspension of Ln 2 (C 2 O 4 ) 3 :Eu 3+ @C@M; separating the liquid suspension to obtain Ln 2 (C 2 O 4 ) 3 :Eu 3+ @C@M solid; Ln 3+  is Y 3+ , Gd 3+  or La 3+ , and x is in a range of 0<x≦0.2, y is in a range of 0<y≦1×10 −2 ; and, 
 mixing sulfur powders with the Ln 2 (C 2 O 4 ) 3 :Eu 3+  @C@M solid according to a molar ratio of S to Ln 3+  which is 1:(2-x), followed by adding a fluxing agent and calcining at 1000° C.-1450° C. to obtain an oxysulfide luminescent material having a general chemical formula of Ln 2—x O 2 S:Eu x   3+ @M y ; Eu 3+ is doped in Ln 2—x O 2 S to form Ln 2—x O 2 S:Eu x    3+ having a porous structure, and @ is coating. 
 
     
     
       5. The method for preparing an oxysulfide luminescent material according to  claim 4 , wherein solute of the solution of salt containing metal M is at least one of PdCl 2 .2H 2 O, AuCl 3 .HCl.4H 2 O, H 2 PtCl 6 .6H 2 O, AgNO 3  and Cu(NO 3 ) 2 ; solvent of the solution is deionized water or ethanol; a concentration of the solution is in a range of 1×10 31 3 −5×10 −2  mol/L. 
     
     
       6. The method for preparing an oxysulfide luminescent material according to  claim 4 , wherein a concentration of the additive is in a range of 1×10 −4 g/mL−5×10 −2 g/mL to the colloid containing M. 
     
     
       7. The method for preparing an oxysulfide luminescent material according to  claim 4 , wherein the reducing agent is at least one of hydrazine hydrate, ascorbic acid, sodium citrate and sodium borohydride; a molar ratio of the reducing agent to M is in a range of 3.6:1-18:1. 
     
     
       8. The method for preparing a an oxysulfide luminescent material according to  claim 4 , wherein the solution of Ln 3+ and Eu 3+ is a mixed solution of Ln(NO 3 ) 3  and Eu(NO 3 ) 3 . 
     
     
       9. The method for preparing a an oxysulfide luminescent material according to  claim 4 , wherein the fluxing agent is anhydrous sodium carbonate; a molar ratio of the fluxing agent to the sulfur powder is in a range of 1:100-1:10.